The 19P2 ligand is a novel peptide found as a ligand to an orphan G protein-conjugated receptor (19P2). It occurs most abundantly in the brain (in particular hypothalamus) and its receptor, namely 19P2, is most abundantly localized in the pituitary gland. Therefore, it is thought to be one of novel hypothalamic hormones (pituitarotropic hormones). Its sequence suggests the occurrence of two 19P2 ligand species, namely (1) 19P2-L31 which is composed of 31 residues (a peptide composed of 31 amino acid residues) and (2) 19P2-L20 which begins with the 12th residue Thr (a peptide composed of 20 amino acid residues) (WO 97/24436). [Hereinafter, the 19P2 ligand composed of 31 amino acid residues is referred to also as “19P2 ligand (1-31) or 19P2-L31” and the 19P2 ligand composed of 20 amino acid residues is referred to also as “19P2 ligand (12-31) or 19P2-L20”.]
The amino acid sequences of bovine, human and rat 19P2 ligand (1-31) species are shown below.
[Bovine 19P2 ligand (1-31)](SEQ ID NO: 1)H-Ser-Arg-Ala-His-Gln-His-Ser-Met-Glu-Ile-Arg-Thr-Pro-Asp-Ile-Asn-Pro-Ala-Trp-Tyr-Ala-Gly-Arg-Gly-Ile-Arg-Pro-Val-Gly-Arg-Phe-NH2 [Human 19P2 ligand (1-31)](SEQ ID NO: 2)H-Ser-Arg-Thr-His-Arg-His-Ser-Met-Glu-Ile-Arg-Thr-Pro-Asp-Ile-Asn-Pro-Ala-Trp-Tyr-Ala-Ser-Arg-Gly-Ile-Arg-Pro-Val-Gly-Arg-Phe-NH2 [Rat 19P2 ligand (1-31)](SEQ ID NO: 3)H-Ser-Arg-Ala-His-Gln-His-Ser-Met-Glu-Thr-Arg-Thr-Pro-Asp-Ile-Asn-Pro-Ala-Trp-Tyr-Thr-Gly-Arg-Gly-Ile-Arg-Pro-Val-Gly-Arg-Phe-NH2
The amino acid sequences of bovine, human and rat 19P2 ligand (12-31) species are shown below.
[Bovine 19P2 ligand (12-31)](SEQ ID NO: 12)H-Thr-Pro-Asp-Ile-Asn-Pro-Ala-Trp-Tyr-Ala-Gly-Arg-Gly-Ile-Arg-Pro-Val-Gly-Arg-Phe-NH2 [Human 19P2 ligand (12-31)](SEQ ID NO: 5)H-Thr-Pro-Asp-Ile-Asn-Pro-Ala-Trp-Tyr-Ala-Ser-Arg-Gly-Ile-Arg-Pro-Val-Gly-Arg-Phe-NH2 [Rat 19P2 ligand (12-31)](SEQ ID NO: 13)H-Thr-Pro-Asp-Ile-Asn-Pro-Ala-Trp-Tyr-Thr-Gly-Arg-Gly-Ile-Arg-Pro-Val-Gly-Arg-Phe-NH2
Disorders of hypothalamic hormones, which are pituitary hormone regulating factors, are associated with various disease states. The 19P2 ligand, which is supposed to be one of hypothalamic hormones, is considered to have some function involving pituitary hormones. Its physiological functions, however, remain to be known yet in many respects. Therefore, development of a system capable of detecting and assaying the 19P2 ligand in an easy and simple manner and with high sensitivity has been earnestly awaited for elucidating the physiological activities of the 19P2 ligand.